Electric smelting.



P. L. T. HROULT. ELECTRIC SMELTING.

APPLICATION FILED APR.25,1J00.

PATENTED JULY 30', 1907.

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. INVENTOR; l

PATENT OFFICE.

PAUL Louis roUssArN'r .snr/ou or LA Pinta, FRANCE, AssiGNon To soorE'rE ELECTRO- BL'IETALLUGIQUE lCRANCAlbE, OF FROGES, FRANCE.

nu. senese.

Patented July 30, 1907.

Application filed pril 25, 1906. Serial llo. 313,580.

To all whom it may com-cm:

Be it; known lthat l', Faun Leurs Tontasag'rri linne ULT, a citiiai'fn of the l l il l La Praz, Savoie, .[fianeeVluw and uselul Improvements in vvhicli the lollowinfj isa speciiication.

This invention aims to provide certain unprovements in the smelling oi 'iron or other trie furnace, and certain improvements in regulating the operation oi an elec ic fur .By this process the composition of the product may he very accn'atelyl determined and controlled, and cast iron ol' any desired composition, containing for i-ample any desired percentage of silicon, may be obtained iront a variety of ores,

ln the smelting o iron ore ina furnace of the usual type having a vertical electrode troni the lower end ol which the current passes to the base oi the l'urnace, the Charge of ore and carbon is pa d through the zone of fusion, and/byadding linie to the charge in e 'cessol' the quantity required to maintain the conipositm'i oi" the slag, the excess linie iornisa scale or liu ing upon the side Walls ol the iurnaco, the thickness oi Whicl in be controllcd'by controlling the supply oi' lim c. scale di minislies the cross-section of the zone ot iusiou or reduction, thus concentrating the energy oi the current through such cross-section, and. causing the electrode to be lifted (by hand er by the usual autonmtic mecha uisin) yto maintain the voltage and ainperagc constant., The increase in the length oi the nono oi fusion increases; also the rate oi reduction .in this zone, and produces a pig ol higher silicon content.

According to nry theory nl' the opt' ation, the trbon which lorins the reducing elenient oi the charge, collects below the electrode in a spougy mass or column extending iront the iuolteu nretal in the bottoni oi the Crucible nearly to the louer end el' the electrode, and the are propt-r extends iroui the lou'er ene` oi the elccti'Ode to the top Oi the column oi' carbon. 'lhe smelt ing may be divided into two steps, first, the inciting oi the various oxids, this being accomplished in the ininiediate neighborhood oll the are und hy radiation oi heat therefrom. Second, the molten oids trickle through the spongy colun'in ol incandescent carbon and are reduced to n greater or less' extent to iron silicon or other metallic elements, the degree ot reduction depending to some extent upon the length ol the column oi carbon through which tney nu molten silicates and other matters i'orin lloat upon the ion throughout the atei carbon, which is also iloating upon the when the cross-section oi thc column of carbon is contrac-ted by introducing a lining or linie upon the walls in the elecec i oi the Crucible, the electrode is raised as above explained to maintain the resistance between the end of the electrode and the base ol the crucible, the incandescent carbon column becomes longer, and this added resistance enables the arc to become a little shorter. Consequent] y there is less heat lor the melting oi the oxids oi the charge, and the operation of the furnace is less rapid, but the oxids which are melted pass through a longer column of carbon and are more completely reduced. Since it is at least approximatelytrue-that the iron is lirst reduced and then the silicon, it follows that the elongation of the zone effusion produces an' `increased silicon content in the product. Therefore slag requires, whereupon the slag will continue to dissolve the scale until its equilibrium isrestored. Be-u cause ot' the elongation of the column of carbon by the contraction ol' the zone of fusion, an increased quantity ol carbon should be supplied to the charge simultaneously with the yincreased quantity of lime.

i he accompanying drawings illustrate the operations in the lurnace in accordance with the theory above outlined. lt is to be understood, however, that these are merely diagrammatic;

liigures l and 2 are vertical sections-oi an electric iurnacc, the first indicating the operation With only suflicient lime to supply the needs oi the slag, and the second indicating the operation with an excessive supply of linie.

lhe Walls constituting the Crucible or body of the lui-nace, comprise a` carbon base A and an upper portion ll, usually of iire-brick, the electrode C entering from the upper end andthe cables being connected respectively to the electrode C and the base A. The tap hole l) is provided for drawing off the molten pig iron from the bottom, and a second tap-holeE at a higherelevation lor drawing oil the slag. The charge F comprises the ore mixed with eolie or other form of carbon, and with limestone or other 'iorrn ol linie7 in the usual quantitics. filter the furnace has been started and settled down to normal Working, the molten iron will collect iu a pool G at the bottom. Floating upon this and extending thereirom to points slightly beyond the end of the' electrode, will be a column ll composed largely or practically enti rel-y oi' carbon in spring-y torni with intersticea through which the masses melted above (nu percolate. The melted oxids and silicates constitul ingl the slag, will collect in a layer .l in the bottom oi the carbon column und loat upon the molten iron. Between the lower end ol the electrode :in d th e upper end oi' the column 1l, is the are l.

,Vhat l have called the zone oiiusion or reduction, extends from the base oi' the electrode to the bottom 0i the urnace, and is of varying Width dependingupon the inclination ei the sides oi the crucible. ln contracting the width of tl zone, it is primarily upon the column oi' carbon which l. werk7 though ordinarily the contraction will extend up and bel-'nr thisl column. The lurnace operates in fact as a combined are and in candeseent furnace, the p. ige or' the current te the surface of the molten iron being li through the ous or other nou-conductimeT :space ro iorm the K, and thence through the in Although there cert the are iiD/cree to the variation in 'the length oi the in eandescent column, :rnd it cannot. be strictly said that 1 operan-np one and not the other, .if the prix h variations enacted by my prof rre n the n e umn- The are is the point or' lost intense heat within the furnace, and by radiatiim. ll around the lower end 0i the electrode the heut meltsl the ore, and the latter 'trieldes in streams or drope through the spongy inclinwhile the remaining unredneed portion Iorms t the slag J Suppose new that the compo does not show suiiciont silicon. in ith the charge a measured qnan'tit f Carbon in addition to that prrwieusljv suo The i.

to combine eheinieall with the olafy ac zeuinulatrs in a scale or lining li (Fig. 2) on the walls or" the' emciblo. The thicknessv of this lining can be accurately deter mined and controlled. The rise of the electrode under thel action of the usual automatic constant current and constant voltage mechanism, will show an experienced operator where the scale is too thick or too thin. The

Vscale has a subsidiaryadvantage in protecting the oidos of the crucible from the. materials in the furnace and preventing the passage of current exceptbyway oi the molten product G and. the bottom oi-the Crucible, thus' enabling the walls oi' the erucible to-Wear a C tider ably longer time than where they are exposed to the direct action of the molten masses and the current. The column of carbon is elongated as :shown7 and the molten ore in passing therethmugh is reduced to a greater extent than before. The gain in energy apv plied to the reduction of the ore, is compensated by a fur. bou enel Supplied' in excess or that required l'or the reactions iuvolverhwill uci in the same watios linie. Silico lor example may lie used inslof'r? of lime.

lhe el'ect oi restrictiivor the Cro of fusion, is lso to croute o, higher heat at the point where the 1 driving action tal/.es place, thus greatly iuj or favoring the reducing action. 'ihe iucie sed hert also facilitates the dissolution oi the carbon iu the iron, nids-in the ilesulluration, and :is 1H the reduction .il the slag to introduce a high percentage ol silicon in the Dit: and thus make it more valuable.'

The irocess may be applied lo other types ol' furnace than that shown, and may be said to include broadly 'the regulating' of the operation ot un electric luruace by 'varying the cron-section ol the zone ol' fusion. Or when upplied to uuu-hing operations, the invention may be considered including.;r broadly the maintaining ol' a. column of carbon or equivalent reducing in terinl between the electrodes and through which th molten uniterial passes, and varying the length ol' column. j Changing the length and diameter of the column ot s me also to alter the effective shape oi the lui-nace to lit the best voltage and amperage for a rire-.u truusiorn'rer or eenerator, so as to lg'et Out of an tion the best commercial result.

Therefore though l have described with great particul-.trity oi' detail eert-iin spec'l embodiments ol the invention, it not to be understood therefrom that .e invention is limited to the'particular embodiments Various modtieations may he madeby those skilled in the art, Without departure from the invention.

l. lr: the' .smelling el iron ore .in an elccrre furnace mirino au ele de from which the current passes to the urs-.e of the furnace, the process which consists in feeding i: i .ire and carbon in such proportion that the curhon n unicum below the elcclw i und the oril is lus-ed :lliure the column und is reduced in passing; therethrough and the molten iron collects :1t thf.` bottom, :1nd add' rg linulo the charco in quantities snllicient to form :i seule ol desired thickness :it the sides of such column, thereby diuln hinp; the cross-sect on of the column and lhus eouwntrallng: the energy ol` the current through :meh eros section, und raising the electrode 0 :is lo ncr rse the length of the column und to increase the degree ol reduction.

2.ln ihn smelling ot' ore in un electric l'urnuce, the process. which eousl'ts in introducing with (he churue :L sull nl: uuzruliry or' the most refractory material thereof 117 l'orm a 'scale ol' desired thickness thus restricting the crosfz- :lion oi the zone of fusion aud thereby concenlrut im; th(l energy ol the current. through such cross-section.

the .iueltimv of ore in un electric furnace, thc ,vlrii-lrconsls f in inlroduchn.; with the charge u rej' muli-rial iu sullicienl'. uuuutily to form u seule of desired ihiclzne. ou the wulls ol' the furnace thus restricting the c* "clion ot' the zone ol' l'usiou und lherc` by cour-entru-liu., the energy of the current lhrough such cross-smttlou.

l. 'l'he process ol' smelling;l in :in electric furnace which consists' in maintaining..Y u column of carbon between the eleetrodf :lud through which the molten umleriul pas es, und urim; lln` length ol` Suid column so :is lo ohlulu saturation ot' the metul with carbon or production o1" silt con l increasingA the lli-u1. i

'lhe prow-ss ol i o 'ululng4 the opel-:lilou ot' :in elec lrc furnace which corrupts in forming.r :i seule on the u'ullsl ul` the turuzuw und varying' the thickness ol" such Heule so to alter the elleclivil shape of Ille zone ot fusion.

o'. '.lhc process oi' regululinu tlnl operation ot' un elec -s'cction of the zolle fori refractory*material i0 form :i Scale of varying thickness upon the sides of the Crucible 0 :is to alter the effective shape of the zene of fusion.

rIn witness whereof, I lmre hereuuio Signed my nume in the presence olf two subscribing witnes, \s.

PAUL LOUIS TOUSSAINT HROULT.

Witnesses ILYAN'rHONY Umm, Finn) WHITE. 

